function calcDistanceBetweenToPoints (point1, point2) {
  const EARTH_RADIUS = 6371e3; // metres

  const latitude1 = point1.lat * Math.PI / 180;
  const latitude2 = point2.lat * Math.PI / 180;

  const deltaLatitude = (point2.lat - point1.lat) * Math.PI / 180;
  const deltaLongitude = (point2.lon - point1.lon) * Math.PI / 180;

  const angle = Math.sin(deltaLatitude/2) * Math.sin(deltaLatitude/2) +
      Math.cos(latitude1) * Math.cos(latitude2) * Math.sin(deltaLongitude/2) * Math.sin(deltaLongitude/2);

  const theta = 2 * Math.atan2(Math.sqrt(angle), Math.sqrt(1 - angle));

  const distance = EARTH_RADIUS * theta;

  return distance; //in metres
}

let result = calcDistanceBetweenToPoints({
  lat: -33.2569755, lon: 151.5492134
},{
  lat: -33.733914, lon: 150.945014
})

console.log(result)